1. Field of Invention
The present invention relates to an on-chip optical interconnection circuit, an electro-optical device, and an electronic apparatus.
2. Description of Related Art
Originally, LSIs (Large Scale Integrated circuits) made progress as integrated circuits having specific functions, such as DRAM (Dynamic Random Access Memory) or MPU (Micro Processing Unit), but with the speedup of MPUs, SRAMs (Static Random Access Memories), used as high-speed cache memories, there has been increased integration into the same chip. Now, by integrating flash memory, DSP (Digital Signal Processor), DRAM, etc. into one chip, the LSIs are being developed into high-performance information processing systems.
An LSI, where integrated circuits having such various functions are formed in the same chip, is called as a system-on-chip (SOC: System On Chip). In such SOC, integrated circuits (circuit blocks) having different functions are formed on one chip in a plane, and the circuit blocks are electrically connected to each other through electrical wiring lines, which are called global wiring lines. The operation speed of the SOC is limited by problems of the signal delay or the increase of power consumption of such global wirings.
If the signal transmission between such circuit blocks is executed using optical signals, it is possible to reduce or prevent problems associated with the signal delay or the increase of power consumption generated from the electrical global wirings and also possible to greatly increase the operation speed of the LSI.
Hence, in order to transmit data using optical signals, an optical transmission device is required to transmit the optical signals emitted from an optical source to a desired place and to input them to a light receiving element, etc. Such related art optical transmission devices include a technology using an optical fiber and a technology using an optical wave-guide formed on a substrate.
However, when optical fiber is used as an optical transmission device, connection with optical components, such as a light emitting element and a light receiving element, becomes complicated resulting in problems of enormous fabrication cost and fabrication time, and difficulty in minimizing the size of optical transmission device.
In contrast, simply connecting an optical transmission medium, a light emitting element, and a light receiving element to each other by using an optical waveguide provided on a substrate may be considered. However, input/output configurations suitable for such an optical waveguide have not been developed yet, and the miniaturization and easy fabrication of an optical transmission device to apply to the inside of an integrated circuit, has also not been attained yet.